1. Field of the Invention
This invention relates to a building block with translucent properties allowing light transmission between spaced first and second boundary surfaces. The translucent properties are provided by discrete translucent members extending between the boundary surfaces and which are spaced form one another. The building block is formed by a cast material filling spaces between the translucent members. The translucent members have sufficient rigidity to remain in position within the building block under the effect of forces applied by the casting of the cast material. The translucent members are interconnected by retainer elements to constitute an integral mechanical structure. The invention is also directed to a method for producing a translucent building block incorporating the integral mechanical structure.
2. Brief Description of the Related Art
The natural inner illumination of buildings is provided by windows created in walls, ceilings or roof structures and containing translucent or transparent materials having weatherproof properties. It is also common to apply transparent, translucent, colored, dyed or water-clear windows of different sizes or aesthetic illumination purposes. Other types of transparent members are also built in between load bearing members like bricks. The number and the sizes of the transparent members are limited by economical, static, heat insulating and mechanical requirements relating to a structure.
The patent document GB 794,864 discloses a translucent building member, where the prefabricated building members, consisting of a translucent member and a framework, are disposed between load bearing building elements. The framework makes the building strength of the member independent from the mechanical strength of the translucent member. However, its disadvantage is that it requires correct fitting of discrete elements at predetermined locations during building of a wall structure.
Embedding of translucent elements into in situ or prefabricated building elements is disclosed in patent document U.S. Pat. No. 3,091,899, where glass strips are embedded randomly in a binding material such that the glass strips guide light between two sides of a building element. The strips project from at least one surface of the building element. Such projecting strips encumber the bricklaying job and the load bearing property of a wall consisting of such elements is limited to a great extent because of the risk of slipping at contact areas between the glass and binding material.
Improved handling and strength properties can be obtained by applying glass fibers arranged in a binding matrix such as concrete. The patent document JP 2006224349 discloses a method comprising the steps of arranging a glass fiber fabric into a mold cavity, filling the mold cavity with concrete to a level of the fabric, and then repeating the procedure until the cavity is filled. Disadvantages of this method are that it is very labor intensive and the application of glass fibers involves extremely high costs.
Publication WO 03/097954 discloses a building block having translucent elements embedded in a structural building material cast in between the two surfaces of a building element, and both ends of the glass fibers are evenly distributed along the two surfaces. From the document US 2007/0074484 A1 a translucent concrete element is known, where glass fibers are spanned between two sheets of an auxiliary framework with spaces between the fibers being filed with a setting material. Thereafter, the sheets of the auxiliary framework are removed and a translucent building block is obtained. Shortcoming of both solutions relates to the costs incurred by the application of glass fibers.
WO 03/097954 discloses a building block and a method of its production, wherein glass fibers are continuously introduced into a longitudinal mold while filling the mold with a binding material matrix and settling the material by vibration and/or pressure. The solidified element is cut across its cross section into elements and thereafter machining the surfaces thus obtained. An advantage of this solution is the continuous production, but applying glass fibers is a shortcoming also in this case.
A further common disadvantage of the above methods is that the translucent members are positioned randomly or the grouping of members is labor intensive or impossible.
The above shortcomings are intended to be resolved by the method disclosed in document JP 1219251, where openings are formed in a flexible or rigid retainer sheet, translucent members, i.e. glass prisms are placed in the openings, and then covering the sheet by a concrete layer having a height according to the height of the prisms. After setting of the concrete layer the flexible sheet is removed and at least one of the surfaces of the member is machined. In the case of a rigid retainer sheet, it remains on the surface. Disadvantages of this method are that the adequate forming of the retainer sheet having no role in the light guidance and requires further work and costs, and when the sheet remains on the building member, it complicates completion of the member and removing it forms wastes. Moreover, in the production of thicker building blocks or when applying slimmer and/or less rigid translucent members, there is no method for fixing the relative position of the translucent members neither to each other nor to the mold, as the retainer sheet is positioned as far as possible from either of the surfaces of the building member, furthermore, the method is inadequate for vertical production of building blocks in the absence of adequate fixing of the translucent members in place during production.
The patent document WO 2006/070214 discloses a light transmitting object and a method for manufacturing the same. The object comprises a substantially non-transparent solid material having rigid (non-flexible) inserts embedded in it, and the inserts can be transparent elements. The surface of the light-transmitting object is partly formed by a part of the surface of the transparent elements. The inserts are fastened to each other either by using adhesive binding material or by the interposition of intermediate spacer members, the whole forming together a skeleton which is embedded in a cast material. The inserts forming the skeleton are fastened to each other by means of bonding. However, a disadvantage of In this solution is that prefabricating of the skeleton by bonding the different inserts requires an intensive and time consuming handwork and indirect materials like gluing agents as well. The shape, size and orientation of the translucent elements can largely differ. In certain embodiments the translucent elements can be plates extending between opposite sides of the building block and dividing it spaced parts, so that the cast material cannot penetrate through the plate and will not constitute a uniform cast body. The lack of a uniform cast body has a negative effect on the mechanical strength, stability and rigidity of the whole block. In further embodiments the elements define very small spacings between them or complex shapes, and the cast material cannot fill such spaces and thus cannot provide the required strength. Due to the way the transparent elements are arranged, it is practically impossible to achieve an accuracy needed to position this skeleton in a mold for producing a light-transmitting object. Furthermore, there is no adequate teaching about how a skeleton is to be fixed in positioned during pouring of a casting material in the mold. Consequently, this method is difficult to us on an industrial scale.